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Understanding Bacteria and Viruses: Classification, Metabolism, and Infection Mechanisms

This chapter explores the fascinating world of bacteria and viruses. It classifies prokaryotes into eubacteria and archaebacteria, detailing their unique structures and metabolic processes, including heterotrophs and autotrophs. The chapter covers the methods of identifying bacteria based on shape and cell wall composition, along with their reproduction through binary fission and conjugation. Additionally, it discusses viral structures, infection types—including lytic and lysogenic cycles—and the implications of retroviruses, viroids, and prions in various organisms.

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Understanding Bacteria and Viruses: Classification, Metabolism, and Infection Mechanisms

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Presentation Transcript

  1. Chapter 19 Bacteria and Viruses

  2. 19-1 BacteriaClassifying Prokaryotes Eubacteria- have cell walls with peptidoglycan, a carbohydrate Archaebacteria- have cell walls with out peptidoglycan -DNA is more similar to eukaryotes -live in harsh environments

  3. Identifying Prokaryotes • Shape • Bacilli (rod shaped) • Cocci (spherical) • Spirilla (spiral and corkscrew)

  4. Identifying Prokaryotes • Cell Walls • Gram-positive: thick peptidoglycan walls • Gram-negative: think peptidoglycan walls • More resistant to antibiotics

  5. Identifying Prokaryotes • Movement • Some move (flagella) • Some don’t move

  6. Metabolic Diversity Heterotrophs Chemoheterotrophs- get carbon and energy from organic molecules Ex: humans Photoheterotrophs- get carbon from organic molecules, get energy from sunlight

  7. Metabolic Diversity Autotrophs Photoautotrophs- get carbon from CO2, get energy from sunlight Ex: cyanobacteria. Chemoautotrophs- get carbon from CO2, get energy from inorganic chemical reactions

  8. Metabolic Diversity

  9. Releasing Energy • Obligate aerobes- require oxygen Ex: Mycobacterium tuberculosis • Obligate anaerobes- do not require oxygen, oxygen kills them Ex: Clostridium botulinum • Faculatative anaerobes- live with or w/o oxygen Ex: E. coli

  10. Growth and Reproduction • Binary fission- parents splits into two daughter cells, asexual reproduction

  11. Growth and Reproduction • Conjugation- a pilus forms between two bacteria, DNA is transferred, sexual reproduction

  12. Growth and Reproduction • Spore Formation- Endospore- thick wall that protects a dormant bacterium

  13. Importance of Bacteria • Decomposers • Nitrogen Fixation • Taking nitrogen from the air and converting it to a useable form

  14. 19-2 Viruses Virus- composed of a DNA or RNA core surrounded by a capsid (protein coat)

  15. Viral Infection Lytic Infection- Virus enters the cells, copies itself, and causes the cell to burst

  16. Viral Infection Lysogenic Infection- virus enters the cell, integrates its DNA into the host DNA, it gets copied when the host replicates Prophage- viral DNA embedded in a host’s DNA

  17. Retroviruses • Genetic information is RNA • In the host RNA is copied to DNA (reverse transcription) • Examples: HIV

  18. Viroids and Prions • Viroids- effect plants, ssRNA w/o a capsid • Damage tomatoes, apples, potatoes • Prions- effect animals, protein infectious particles • Ex: mad cow disease, Creutzfeldt-Jakob disease

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